ICES Identification Leaflets for Plankton

Fiches d’ldentification du Plancton

LEAFLET NO. 183 Polychaeta: Larvae

Family: Phyllodocidae

by EGINHARD HUSEMANN Ruhr-Universitat Bochum Lehrstuhl fur Spezielle Zoologie, AG Entwicklungsphysiologie der Tiere D-44780 Bochum, Germany Correspondence: WaldstraDe 62, D-32105 Bad Salzuflen, Germany

Editor J. A. LINDLEY Natural Environment Research Council Plymouth Marine Laboratory Prospect Place, West Hoe, Plymouth PL1 3DH, England, United Kingdom

INTERNATIONAL COUNCIL FOR THE EXPLORATION OF THE SEA

~ ~~ CONSEIL INTERNATIONAL POUR L’EXPLORATION DE LA MER

Palagade 24, DK-1261 Copenhagen K, Denmark https://doi.org/10.17895/ices.pub.5163 1999 ISSN 1019-1097 C Figure 1. a: Eteone cf. longa: dorsal view of nectochaeta with 5 segments, segment 6 in formation. b: Mysta barbata: dorsal view of nectochaeta with 6 segments. c-d: Phyllodoce mucosa; c: parapodium of a median segment, lateral view; d: late metatrochophore with 12 segments, dorsal view. Scale bar: la, b, d: 100 pm: lc: 20 pm.

2 Figure 2. a-b: Phyllodoce rosea: a: late metatrochophore with 17 segments, dorsal view; b: parapodium of a median segment, lateral view. c: Pseudomystides limbata: dorsal view of early nectochaeta with 6 segments. d: Eulalia viridis: dorsal view of nectochaeta with 7 segments. Scale bar: 2a, c, d: 1OOpm; 2b: 20pm.

a

Figure 3. Eumida sunguinea: late nectochaeta with 9 segments, dorsal view. b: Sige fusigera; erpochaeta with 7 segments, dorsal view. Scale bar: 100 pm.

3 Family Phyllodocidae Key to genera and species 1. Prostomium with 4 antennae; Introduction 2 pairs of tentacular cirri in the Phyllodocids are very common errant polychaetes. They anteriormost segment; parapodia are distributed all over the world and inhabit all types of with dorsal cirri from segment 3 2 substrates. Spawning takes place free in the water column Prostomium with 4-5 antennae; (Rasmussen, 1956) or the eggs are laid within protective 3-4 pairs of tentacular cirri in the structures (own observation). A planktonic larval stage anteriormost segments; parapodia occurs in all phyllodocid species for which reproductive with dorsal cim from segment 4 3 details are known. Pelagic life is species-specific at different developmental stages and can last for less than two weeks or take more than one month. The larvae 2. Dorsal tentacular cirri as long as Eteone cf. longa are lecithotrophic, planktotrophic, or variable, changing ventral tentacular cirri; 2 pairs of (Fabricius, from lecithotrophic to planktotrophic. Planktotrophic eyes (Fig. la) 1780) larvae feed on phytoplankton and small zooplankton. Dorsal tentacular cirri longer than Mysta barbata During their pelagic phase the larvae gradually develop ventral tentacular cirri; 1 pair of Malmgren, many characteristics of the adult. This process culminates eyes (Fig. lb) 1865 in metamorphosis to a benthic organism and is often accompanied by profound morphological changes. 3. Metatrochophores and Genus An illustrated key for the larvae of eight species of nectochaetae with 4 pairs of Phyllodoce Phyllodocidae occurring in the southeastern North Sea tentacular cirri and 4 antennae 4 is provided. Detailed illustrated descriptions are given Metatrochophores with 3 pairs of to ensure accurate identification. The key and the tentacular cirri and 4 antennae, descriptions are based on the earliest or the most typical late nectochaetae with 34pairs developmental stage exhibiting all features required in of tentacular cirri and 5 antennae; the identification process. Species determination may be median antenna situated between impossible in earlier developmental stages. eyes, sometimes very small 5 Larvae were collected by horizontal near-surface sampling with a net of 75pm mesh size. The live material was examined under a dissecting stereomicro- 4. Metatrochophores and scope at magnifications from 10 to 40x. For the obser- nectochaetae with less than 15 vation of some morphological details a light microscope segments; yellow pigment at the with magnifications from 40 to lOOOx was used. All prototroch and dorsally at the descriptions were based on live material. For all species, anteriormost segments; ventral Phyllodoce information is given on the season when the larvae are cirri short, broad in nectochaetae rnucosa represented in the plankton of the German Bight. (Fig. 1c-d) IZlrsted, 1843 Further information can be found in Plate (1992) and Metatrochophores and Husemann (1992). Systematic classification and species nectochaetae with more than 15 names follow the recent revisions of Wilson (1988) and segments; red pigmented Pleijel (1991, 1993). prototroch; 2 rows of red chromatophores may occur at the Phyllodoce dorsum; ventral cirri slender, rosea elongate in nectochaetae (McIntosh, General characteristics of phyllodocid (Fig. 2a-b) 1877) larvae The earliest developmental stage identifiable is the late 5 Segment 1 fully developed metatrochophora to early nectochaeta. These larvae dorsally; all segments separated possess 6-20 segments, a prostomium with 24eyes and from each other; stout larvae; 4-5 antennae, 24pairs of tentacular cirri and para- proboscis with numerous large podia with parapodial lobes, and dorsal and ventral papillae 6 cirri. Setae are compound and occur from segment 2 or Segment 1 dorsally reduced and 3. One pair of pygidial anal cirri present. A papillate fused with segment 2; slender proboscis may be visible in the anterior part of the body larvae; proboscis without large in front of the gut. papillae

4 Metatrochophores and nectochaetae with 3 pairs of Genus Mystu tentacular cirri; ventral tentacular cirri of segment 2 flat and Mysta harbata (Fig. 1 b) proximal broadened, remaining Pseudomystides Synonym: Eteone barbata (Malmgren, 1865) tentacular cirri cirriform; gut with limhata yolk granules; prototroch absent (Saint-Joseph, Pelagic metatrochophores with 6 segments have a in nectochaetae (Fig. 2c) 1888) length of 400pm. Late metatrochophore and nccto- Metatrochophores with 3 pairs of chaeta stages with truncated conical prostomium; 4 tentacular cirri; late nectochaetae antennae; 1 pair of dark-red eyes; well-developed proto- with 4 pairs of cirriform troch; telotroch present; 2 pairs of tentacular cirri in tentacular cirri; gut without yolk ~~l~l~~viridis segment 1; setae and ventral cirri from segment 2 and granules; prototroch persists in (~i~~~~~~,dorsal cirri from segment 3; anal cirri elongated, ovoid. nectochaetae (Fig. 2d) 1767) Dorsal tentacular cirri become 1.5 times as long as ventral cirri in late nectochaeta stage. Larvae olive- Yellow pigment at the prototroch; brown pigmented with darker brown pygidium. gut greenish-yellow; all tentacular Seasonal occurrence: September. cirri cirriform; parapodial lobe Eumida without prolongation in sanguinea nectochaetae (Fig. 3a) (Orsted, 1843) Genus Pseudomystides Prototroch unpigmented; gut dark brown; ventral tentacular cirri of Pseudomystides limbata (Fig. 2c) segment 2 f flat and proximal Synonym: Mystides (Mesomystides) limbata broadened, remaining tentacular Saint-Joseph, 1888 cirri cirriform; prolongation of the upper presetal part of the Sigefusigera Earliest planktonic stage is a trochophore; latest stage is a parapodial lobe in nectochaetae Malmgren, metatrochophore with 7 segments and length of 460 Fm. (Fig. 3b) I865 Trochophores are oval; round episphere, dome-shaped with 1 pair of red eyes; prototroch consists of long cilia; gut with yolk granules. Metatrochophores and necto- chaetae with truncated, rectangular prostomium; 4 antennae; 2 pairs of red eyes of which the anterior pair is much smaller than the posterior pair and near to the Description of larvae median; 1 pair of tentacular cirri in segment 1 and 2 pairs in segment 2; ventral tentacular cirri of segment 2 are flat with proximal broadening, remaining tentacular cirri Genus Eteone cirriform; setac from segment 2, ventral cirri from Eteone cf. longa (Fig. la) segment 3 and dorsal cirri from segment 4; anal cirri ovoid, twice as long as broad; median pygidial papilla Earliest pelagic stage is a trochophore; latest stage is present. All larval stages with brown pigmentation, a nectochaeta with 7 segments and length of 630pm. pygidium dark-brown. Ventral tentacular cirri in segment Trochophores are oval; episphere dome-shaped with 2 become increasingly flattened in older stages, other 1 pair of red eyes; prototroch well developed; gut tentacular cirri remain cirriform. Proboscis with papillae with yolk granules. Late metatrochophore and visible in late nectochaeta stage. At time of settlement nectochaeta stages with truncated, conical prosto- some individuals exhibit a small median antenna between mium; 4 antennae; 2 pairs of red eyes of which the the eyes. Seasonal occurrence: June to August. anterior pair is much larger than the posterior pair; telotroch present; 2 pairs of tentacular cirri of equal length in segment 1; setae and ventral cirri from Genus Eululiu segment 2 and dorsal cirri from segment 3; anal cirri short, ovoid. Proboscis visible in late necto- Eulalia viridis (Fig. 2d) chaeta stage. Larvae brown with green and brown chromatophores distributed over whole body; Earliest planktonic stage is a trochophore; latest stage highest density of chromatophores in a median line is a metatrochophore with 6 segments and length of on prostomium, and at pygidium. Seasonal occur- 350 pm. Trochophores are oval; episphere trapezoid, rence: February to April. with 1 pair of red eyes; prototroch consists of long

5 cilia. Metatrochophores and nectochaetae with rectan- cular cirri cirriform; setae from segment 2, ventral cirri gular prostomium; 4 antennae; 1 pair of red eyes; 1 from segment 3, and dorsal cirri from segment 4. Upper pair of cirriform tentacular cirri in segment 1 and 2 presetal part of the parapodial lobe prolongates in the pairs of segment 2; setae from segment 2, ventral cirri nectochaeta. One pair of slender, boddle-shaped anal from segment 3, and dorsal cirri from segment 4; 1 cirri. Larvae pale, with dark-brown gut. Nectochaetae pair of rounded anal cirri. One median antenna arises with median antenna between eyes; proboscis with ring anterior to the eyes in the late nectochaeta stage. of distally located papillae; small, median anal papilla. Larvae pale, with olive-brown to dark-green gut and A 4th pair of tentacular cirri originating in segment 3 olive-brown pigmented pygidium. A 4th pair of tenta- becomes visible in benthic juveniles with at least cular cirri appears in segment 3 in benthic juveniles 9 segments. Seasonal occurrence: September to comprising about 19 segments. Seasonal occurrence: November. April to June. Genus Phyllodoce Genus Eumida Phyllodoce mucosa (Fig. lc-d) Eumida sanguinea (Fig. 3a) Earliest planktonic stage is a trochophore; latest stage is Synonym: Eulalia sanguinea Orsted, 1843 a nectochaeta with 13 segments and length of 1.1 mm. Trochophores spherical, blue-green with a yellow Earliest planktonic stage is a trochophore; latest stage is pigmented ring posterior to the prototroch, with apical a nectochaeta with 14 segments and length of 1.1 mm. tuft. Metatrochophores and nectochaetae with trian- Trochophores are oval, greenish coloured with yellow- gular prostomium; 4 antennae; 1 pair of red eyes; proto- white pigment spots arranged in a ring posterior the troch present; segment 1 dorsally reduced, segments 2 prototroch. Metatrochophores and nectochaetae with and 3 dorsally fused; 4 pairs of cirriform tentacular cirri conical, dome-shaped prostomium; 4 antennae; 2 pairs in anteriormost segments; setae from segment 2, ventral of red eyes of which the anterior pair is much smaller cirri from segment 3, and dorsal cirri from segment 4; 1 than the posterior pair and near to the median; the 2 pair of cirriform anal cirri. The hyposphere forms a fold pairs of eyes fused in the nectochaeta; prototroch posterior to the prototroch, dorsally covering segments present; 1 pair of cirriform tentacular cirri in segment 1 1-3. Distal part of proboscis covered with soft papillae, and 2 pairs in segment 2; setae present from segment 2, visible in nectochaeta stage. Larvae have pale greenish ventral cirri from segment 3, and dorsal cirri from colour, dorsally with yellow pigment in segments 2 and segment 4. One pair of slender, tapering anal cirri. 3; 2 rows of yellow pigmented spots occur intersegmen- Larval body greenish with yellow-white pigment tally posterior to segment 5. Dorsal cirri of nectochaeta posterior to the prototroch and dark brown gut. Proboscis with a ring of distally located papillae, first are subrectangular; ventral cirri broad distally pointed, slightly longer than setal lobe. Seasonal occurrence: differentiated in the late metatrochophore stage. A median antenna appears in the late nectochaeta, when March to June. larvae become benthic. The 4th pair of tentacular cirri originates in segment 3 in the late erpochaeta. Seasonal occurrence: June to August. Phyllodoce rosea (Fig. 2a-b) Synonym: Anaitides subulifera Eliason, 1962 Genus Sige Earliest planktonic stage is a trochophore; latest stage is a nectochaeta with 20 segments and length of 1.5 mm. Trochophores ovoid, pale coloured, with red Sigefusigera (Fig. 3b) pigment spots arranged in a ring posterior to well- Earliest pelagic stage is a trochophore; latest stage is a developed prototroch. Metatrochophore and necto- metatrochophore with 7 segments and length of 400 pm. chaeta stages with rounded prostomium; 4 antennae; 2 Trochophores are oval; episphere dome-shaped with 1 pairs of red eyes of which the anterior pair is much pair of red eyes; prototroch with long cilia; gut dark- smaller than the posterior pair and near to the brown coloured. Metatrochophores and nectochaetae median; prototroch and telotroch present; segment 1 with rounded, triangular prostomium; 4 antennae; 1 dorsally reduced, segments 2 and 3 fused; 4 pairs of pair of large, red eyes; 1 pair of cirriform tentacular cirriform tentacular cirri in anteriormost segments; cirri in segment 1; ventral tentacular cirri of segment 2 setae from segment 2, ventral cirri from segment 3, sometimes flat and proximally broaden, dorsal tenta- and dorsal cirri from segment 4; gut with numerous

6 yolk granules. Larvae nearly transparent with a ring References of red pigment spots posterior to prototroch and telo- Husemann, E. 1992. Bestandsaufnahme und Larvenentwick- troch, and additional 2 rows of red pigment spots lung der im Helgolander Plankton auftretenden Poly- on dorsum. Proboscis with smooth, distal part; a chaeten und Polychaetenlarven- Ordnungen: Phyllodocida, proximal part covered with rows of hard papillae, Oweniida, Terebellida, Sabellida und Familien mit unsi- appearing in late metatrochophore. Nectochaetae with cherer Ordnungszugehorigkeit. Diss. Univ. Bochum. 222 pp. pair of rounded, short anal cirri; subrectangular dorsal Plate, S. 1992. Untersuchungen zum zeitlichen Auftreten, zur cirri; subulate ventral cirri, more than twice as long as Abundanz und Entwicklung meroplanktischer Polychaeten- parapodial lobe and with extremely fine extended tips. larven im Gebiet Helgoland Reede- Ordnungen: Orbiniida, Seasonal occurrence: June to September. Spionida und Capitellida. Diss. Uni. Bochum. 235 pp. Pleijel, F. 1991. Phylogeny and classification of the Phyllodocidae (Polychaeta). Zool. Scr., 20: 225-261. Pleijel, F. 1993. Polychaeta Phyllodocidae. Mar. Invest. Scand., 8: 1-159. Acknowledgements Rasmussen, E. 1956. Faunistic and biological notes on marine My special thanks to Dr S. Plate, who helped me sort invertebrates. 111. The reproduction and larval development of some polychaetes from Isefjord with some faunistic notes. the larvae from the plankton samples. I also thank the Biol. Meddr., 23: 1-84. Biologische Anstalt Helgoland for their friendly assis- Wilson, R. S. 1988. A review of Eteone Savigny, 1820, Mysta tance and two anonymous referees for their helpful Malmgren, 1865 and Hypereteone Bergstrom, 1914 (Poly- comments on an earlier version of the manuscript. chaeta: Phyllodocidae). Mem. Mus. Victoria, 49: 385431.

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